diff --git a/lib/set.rb b/lib/set.rb
index df1e68d081..a515dacb0e 100644
--- a/lib/set.rb
+++ b/lib/set.rb
@@ -507,7 +507,7 @@ class Set
   # the element as parameter.  Returns an enumerator if no block is
   # given.
   def each(&block)
-    block or return enum_for(__method__) { size }
+    block_given? or return enum_for(__method__) { size }
     @hash.each_key(&block)
     self
   end
@@ -582,7 +582,7 @@ class Set
   # Equivalent to Set#delete_if, but returns nil if no changes were
   # made. Returns an enumerator if no block is given.
   def reject!(&block)
-    block or return enum_for(__method__) { size }
+    block_given? or return enum_for(__method__) { size }
     n = size
     delete_if(&block)
     self if size != n
@@ -591,7 +591,7 @@ class Set
   # Equivalent to Set#keep_if, but returns nil if no changes were
   # made. Returns an enumerator if no block is given.
   def select!(&block)
-    block or return enum_for(__method__) { size }
+    block_given? or return enum_for(__method__) { size }
     n = size
     keep_if(&block)
     self if size != n